1. Field of the Invention
The present invention relates to an ion beam inspection apparatus, an ion beam inspecting method, a semiconductor manufacturing apparatus and an ion source apparatus, and relates to, for example, a technique for supporting the position adjustment of an extraction electrode that extracts ions implanted into a semiconductor from an ion source.
2. Description of the Related Art
A semiconductor integrated circuit is manufactured in such a manner that ions are implanted into a semiconductor wafer to form p-type regions or n-type regions.
In the implantation of ions, there has been employed a semiconductor manufacturing apparatus that conducts a series of process steps such as generation of ions by heating a gas to a high temperature, extraction of generated ions by the extraction electrode, sorting of extracted ions by a mass analyzer, focusing of sorted ions, and irradiation of the wafer with the focused ions.
In order to operate the semiconductor manufacturing apparatus, it is necessary to conduct many kinds of adjustments, one of which is to adjust the position of the extraction electrode.
FIG. 8A is a conceptual diagram showing the outline of an ion source apparatus.
An ion source apparatus 1 has an ion source 6 and an extraction electrode 3 that extracts ions from the ion source 6 in the interior of a cylindrical housing 5.
The ion source 6 includes a disc-shaped fitting flange 4, a cylindrical member 7 that is disposed on the central axis of the fitting flange 4, and a source head 2 that is disposed on a leading end of the cylindrical member 7.
The ion source 6 is fitted to the housing 5 in such a manner that the source head 2 is inserted into the housing 5 and the fitting flange 4 is fixed on one end surface of the housing 5.
An O-ring (not shown) is equipped between the fitting flange 4 and the end surface of the housing 5 so as to keep the airtightness in the interior of the housing 5.
A gas intake not shown is defined in an end surface of the fitting flange 4. The gas that has been taken in from the gas intake is heated to a high temperature by means of a filament within the source head 2 to generate ions.
The extraction electrode 3 is disposed at a certain distance from the end surface of the source head 2, and applied with a high voltage. The extraction electrode 3 is set to a negative potential when the ions that are generated in the source head 2 are positive ions. On the other hand, the extraction electrode 3 is set to a positive potential when the negative ions are generated, so as to extract ions from the source head 2 and accelerate the ions to form an ion beam as indicated by an arrow.
The extraction electrode 3 is formed with an opening 16 called aperture having a substantially rectangular cross section, and an ion beam 15 is formed according to the shape of the opening, and introduced to the interior of the semiconductor manufacturing apparatus.
An arm 18 is fitted to a lateral side of the extraction electrode 3 in a direction perpendicular to the paper surface. The arm 18 is rotated around the central axis of the arm 18 or traveled horizontally in a central axial direction of the arm 18, thereby making it possible to adjust the position of the extraction electrode 3.
In the ion source apparatus 1, in order to enhance the generation efficiency of the ion beam 15, it is important to conduct the centering adjustment that matches the central axis of the ion source 6 with the central axis of the opening 16.
For example, as shown in FIG. 8B, when the extraction electrode 3 is inclined with respect to the central axis of the ion source 6, the ion beam 15 is slanted and nonuniformily hits the opening 16, causing waste of the ions, wear-out of the opening 16, and increase of deposit that adheres to the extraction electrode 3.
The centering adjustment is required every time the maintenance work such as cleaning of the ion source apparatus 1, exchange of a filament of the source head 2, or exchange of the extraction electrode 3 is conducted. Up to now, the centering adjustment has been conducted as follows.
The semiconductor manufacturing apparatus is completely stopped, the ion source apparatus 1 is removed, and parts such as the filament are exchanged. Then, after the position of the extraction electrode 3 is measured by the aid of mechanical tool such as a slide gauge or a scale, and coarsely adjusted, the ion source apparatus 1 is fitted to the semiconductor manufacturing apparatus.
Subsequently, after a high vacuum is created in the entire semiconductor manufacturing apparatus in several hours, the semiconductor manufacturing apparatus is actually irradiated with the ion beam 15 from the ion source apparatus 1. Then, the position of the extraction electrode 3 is finely adjusted so that a value of current that arises in the extraction electrode 3 (suppression current) becomes minimum.
When the ion beam 15 hits the extraction electrode 3, current flows into the extraction electrode 3 from the source head 2. Accordingly, the size of the current value corresponds to the quantity of the ions that hit the extraction electrode 3.
In the above method, a high vacuum must be created in the semiconductor manufacturing apparatus, and the ion beam 15 must be actually irradiated in the semiconductor manufacturing apparatus. For that reason, a centering adjustment using a laser beam as disclosed in JP 64-14855 A has been proposed.
In the above technique, a light source is arranged on the end surface of the source head 2, and a slit through which a light from the light source is transmitted is arranged in the extraction electrode. Also, a detector for the transmitted light is arranged on a side of the slit opposite to the extraction electrode.
The position of the extraction electrode is adjusted so that the intensity of the transmitted light becomes the largest, to thereby conduct the centering adjustment.
However, because the temperature of the source head 2 and the extraction electrode 3 becomes high, which exceeds 1,000 [° C.] during the operation, it is extremely difficult to locate the light source and the detector in the ion source apparatus 1. For that reason, the possibility of actual use seems quite low.
Incidentally, the inventor of the present invention has found out that the inclination of the central axis of the ion source 6 with respect to the central axis of the extraction electrode 3 due to the uneven fitting of the fitting flange 4 as shown in FIG. 8C also causes deterioration in the generation efficiency of the ion beam 15.